impeller::DashedLinePathSource Class Reference

A PathSource that generates the various segments of a dashed line. More...

#include <dashed_line_path_source.h>

Inheritance diagram for impeller::DashedLinePathSource:

Public Member Functions
	DashedLinePathSource (Point p0, Point p1, Scalar on_length, Scalar off_length)
	~DashedLinePathSource ()
FillType	GetFillType () const override
Rect	GetBounds () const override
bool	IsConvex () const override
void	Dispatch (PathReceiver &receiver) const override
Public Member Functions inherited from impeller::PathSource
virtual	~PathSource ()=default

Detailed Description

A PathSource that generates the various segments of a dashed line.

Definition at line 15 of file dashed_line_path_source.h.

Constructor & Destructor Documentation

DashedLinePathSource()

impeller::DashedLinePathSource::DashedLinePathSource	(	Point	p0,
		Point	p1,
		Scalar	on_length,
		Scalar	off_length
	)

Definition at line 9 of file dashed_line_path_source.cc.

    : p0_(p0), p1_(p1), on_length_(on_length), off_length_(off_length) {}

~DashedLinePathSource()

impeller::DashedLinePathSource::~DashedLinePathSource ( )

default

Member Function Documentation

Dispatch()

void impeller::DashedLinePathSource::Dispatch ( PathReceiver &  receiver ) const

overridevirtual

Implements impeller::PathSource.

Definition at line 29 of file dashed_line_path_source.cc.

                                                                {
  // Exceptional conditions:
  // - length is non-positive - result will draw only a "dot"
  // - off_length is non-positive - no gaps, result is a solid line
  // - on_length is negative - invalid dashing
  // Note that a 0 length "on" dash will draw "dot"s every "off" distance
  // apart so we still generate the dashing for that case.
  //
  // Note that Canvas will detect these conditions and use its own DrawLine
  // method directly for performance reasons for a single line, but in case
  // someone uses this PathSource with these exceptional cases, we degenerate
  // gracefully into a single line segment path description below.
  Scalar length = p0_.GetDistance(p1_);
  if (length > 0.0f && on_length_ >= 0.0f && off_length_ > 0.0f) {
    Point delta = (p1_ - p0_) / length;  // length > 0 already verified
 
    Scalar consumed = 0.0f;
    while (consumed < length) {
      receiver.MoveTo(p0_ + delta * consumed, false);
 
      Scalar dash_end = consumed + on_length_;
      if (dash_end < length) {
        receiver.LineTo(p0_ + delta * dash_end);
      } else {
        receiver.LineTo(p1_);
        // Should happen anyway due to the math, but let's make it explicit
        // in case of bit errors. We're done with this line.
        break;
      }
 
      consumed = dash_end + off_length_;
    }
  } else {
    receiver.MoveTo(p0_, false);
    receiver.LineTo(p1_);
  }
}

References impeller::TPoint< T >::GetDistance(), impeller::PathReceiver::LineTo(), and impeller::PathReceiver::MoveTo().

Referenced by impeller::testing::TEST().

GetBounds()

Rect impeller::DashedLinePathSource::GetBounds ( ) const

overridevirtual

Implements impeller::PathSource.

Definition at line 21 of file dashed_line_path_source.cc.

                                           {
  return Rect::MakeLTRB(p0_.x, p0_.y, p1_.x, p1_.y).GetPositive();
}

References impeller::TRect< T >::GetPositive(), impeller::TRect< Scalar >::MakeLTRB(), impeller::TPoint< T >::x, and impeller::TPoint< T >::y.

Referenced by impeller::testing::TEST().

GetFillType()

FillType impeller::DashedLinePathSource::GetFillType ( ) const

overridevirtual

Implements impeller::PathSource.

Definition at line 17 of file dashed_line_path_source.cc.

                                                 {
  return FillType::kNonZero;
}

References impeller::kNonZero.

Referenced by impeller::testing::TEST().

IsConvex()

bool impeller::DashedLinePathSource::IsConvex ( ) const

overridevirtual

Implements impeller::PathSource.

Definition at line 25 of file dashed_line_path_source.cc.

                                          {
  return false;
}

Referenced by impeller::testing::TEST().

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The documentation for this class was generated from the following files:

• impeller/geometry/dashed_line_path_source.h
• impeller/geometry/dashed_line_path_source.cc